Nibbled to Death

How an infectious amoeba kills cells by snacking on them

University of Virginia researchers have found a parasitic infection that kills human cells by nibbling them to death, a surprising discovery that suggests a broader range of organisms could use this method than originally thought.

Most infectious organisms release a toxin to kill cells, then engulf and consume the cells. Scientists had assumed that Entamoeba histolytica, which causes amebiasis, an infection that causes potentially fatal diarrhea, worked in the same way. But research at the School of Medicine showed that the infectious amoeba actually binds to human cells and begins nibbling off pieces of the cell’s membrane until the cell becomes unstable and dies. The amoeba then detaches to find another live cell to nibble. The amoeba is one of only a handful of organisms that scientists have seen work this way, but the research suggests that there may be more.

“The surface protein on the amoeba that allows it to bind is also used for nibbling,” postdoctoral fellow Katherine S. Ralston says. “If we can inhibit that, we could get at a way to treat the infection.”